I have a scenario where appliances running Debian may have multiple network interfaces. I want my eth0 interface to get its address via SLAAC configuration, but I want the remaining interfaces to only have their link-local or manually configured IPv6 addresses.

UPDATE: actually, that just disables the creation of an IPv6 IP address - it still gets, for example, default routes for that interface. To disable SLAAC on the interface altogether, apparently what you actually want is net.ipv6.conf.eth1.accept_ra=0